It could happen.

The Ebloa virus has many different strains, but evolution and dna growth could make them very dangerous than the already are. Yes, we are close to a vaccine but if someone leaves sierra leone or guinea and nobody notices, we have a very dangerous and widespread situation of global proportions. Lets say Ebola started to raise the dead ( phsychopathic reanimation.) people wouldnt really notice in Africa, then africa would be destroyed, and the world would panic, get infected, then die off, since authorities cant really protect from the zombies. In conclusion, the Ebola virus is one of the most contagious diseases ive ever seen.